As is known, conventional dishwashers perform a washing process whose programme sequence generally consists of at least one “Pre-wash” partial programme step, a “Clean” partial programme step, at least one “Intermediate wash” partial programme step, a “Clear wash” partial programme step and a “Dry” partial programme step. To increase the cleaning effect the rinsing fluid or rinsing liquor is heated before or during a partial programme step. The rinsing fluid is normally heated by means of electrical heating elements. Different drying systems are known for drying the items to be washed in a dishwasher.
DE 20 16 831 discloses, for example, a dishwasher of the type already mentioned in which the air is conducted from the washing container through a sealable opening in the wall of the washing container on reversibly dehydratable material, and from there to the outside through an opening. Desorption of the reversibly dehydratable material takes place during the non-operating phase of the device, the water vapour formed thereby being conducted to the outside through the opening. The dishwasher described is disadvantageous from the energy viewpoint because the regeneration of the reversibly dehydratable material takes place during a non-operating phase of the appliance, i.e. at a time when none of the partial programme steps already described is being carried out. A further disadvantage consists in the fact that the possibility of damage to the surrounding kitchen furniture cannot be ruled out as a result of the discharge of the water vapour formed during regeneration of the reversibly dehydratable material to the outside. In this case the regeneration is associated with an additional energy requirement which is additional to the energy required during the partial programme steps.
In order to minimise the energy expended during operation of a dishwasher, DE 103 53 774.0 of the applicant discloses a dishwasher with a washing container and devices for washing dishes by means of rinsing liquor which is provided with a sorption column which is connected in an air-conducting manner to the washing container and encompasses reversibly dehydratable material, where on the one hand the sorption column is used for drying the dishes and on the other hand the thermal energy utilised for desorption of the sorption column is used to heat the rinsing liquor and/or the dishes in the washing container, at least in part.
To solve the same problem DE 103 53 775.9 of the applicant proposes conducting air from a processing space and/or from ambient air through a sorption column and into the processing space for operating an appliance in the at least one “Dry” partial programme step, where the sorption column encompasses reversibly dehydratable material and moisture is extracted from the air during its through-passage.
Heating the items to be washed in the partial programme step preceding the “Dry” partial programme step is no longer normally necessary due to the use of reversibly dehydratable material with a hydroscopic property, e.g. zeolith. This allows a substantial saving in energy.
EP 0 358 279 B1 discloses a dishwasher with a closed drying system in which the air from the washing container circulates through a drying device that can be regenerated by heating and from this device back into the washing container. The drying device is assigned to the heater arranged outside the washing container for the rinsing liquor, this heater preferably being a geyser. The outlet of the washing container is located in the ceiling of the washing container, whilst the inlet is integrated in the washing tank of the washing container. The outlet of the washing container is connected to the sorption drying device by means of an air duct. Since the sorption drying device is assigned to the heater for the rinsing liquor it is arranged in a region underneath the rinsing tank.